The pretty confusing "buffer.h" was in fact not the place to look for
the definition of "struct buffer" but the one responsible for dynamic
buffer allocation. As such it defines the struct buffer_wait and the
few functions to allocate a buffer or wait for one.
This patch moves it renaming it to dynbuf.h. The type definition was
moved to its own file since it's included in a number of other structs.
Doing this cleanup revealed that a significant number of files used to
rely on this one to inherit struct buffer through it but didn't need
anything from this file at all.
This file is to openssl what compat.h is to the libc, so it makes sense
to move it to haproxy/. It could almost be part of api.h but given the
amount of openssl stuff that gets loaded I fear it could increase the
build time.
Note that this file contains lots of inlined functions. But since it
does not depend on anything else in haproxy, it remains safe to keep
all that together.
